Microbial Quality and Molecular Identification of Enterotoxigenic Staphylococcus Strains Isolated from Dried, Smoked, and Braised Fish Sold in Ouagadougou Markets

Background: The investigation of toxin genes in strains involved in staphylococcal food poisoning contributes to food safety. The aim of this study was to isolate and identify enterotoxigenic Staphylococcus strains from dried, smoked, and braised fish sold in Ouagadougou markets. Methodology: Staphylococci were isolated using standard microbiology methods. Staphylococcus strains were identified using API Staph kit (Reference # 20500, BioMerieux S.A., Marcy l'Etoile, France). The molecular identification of isolated Staphylococcus aureus strains was specifically confirmed by PCR using the Staur4 and Staur6 primers. The genes encoding enterotoxins, enterotoxin-like toxins, exfoliative toxins, and TSST-1 toxin were detected by multiplex PCR using specific primers from Inquaba Biotec West Africa Ltd, Africa's Genomics Company. Results: The results of the microbiological quality assessment indicated that most of the samples analyzed were found to be of unsatisfactory microbiological quality according to the Staphylococcus aureus microbiological criteria (m = 102). Overall, only 12.55% of samples were satisfactory, while 97.45% were unsatisfactory. The STAPH API gallery allowed the identification of the following species: Staphylococcus aureus, Staphylococcus xylosus, Staphylococcus lugdunensis, Staphylococcus hominis, Staphylococcus haemolyticus, Staphylococcus lentus, Staphylococcus sciuri and Staphylococcus capitis. Of the 108 Staphylococcus isolates, 81 (75%) showed at least one (1) toxin gene. Among the 21 toxin genes tested in this study, 20 genes were detected in all strains analyzed. The staphylococcal toxin genes detected were present in both Staphylococcus aureus and the other coagulase-negative strains isolated in this study. In addition, these genes are found individually or in association in certain strains. The most frequent genes detected in toxin gene-positive strains were: the tsst-1 gene in 45 isolated strains (41.7%), sei (16/14.8%), seg (13/12%), ser (7/6.5%) sec (6/5.5%), and sea (5/4.6%) for staphylococcal enterotoxins, seln (14/12.9%), selq (8/7.4%), for enterotoxin-like toxin gene and eta (3/2.7%) for exfoliative toxin genes. Conclusion: This study highlighted the pathogenicity of Staphylococcus strains isolated from dried, smoked, and braised fish sold in Ouagadougou markets. Monitoring toxin-producing strains of Staphylococcus is invaluable for better prevention of food poisoning.

Phenotypic and Molecular Characterization of Staphylococcaceae and Enterobacteriaceae Species Isolated from Smoked, Dried, and Braised Fish Marketed in Ouagadougou

Background: To preserve its nutritional properties, fish must have good sanitary quality. The objective of this study was to investigate some pathogens contaminating smoked, dried, and braised fish marketed in Ouagadougou. Methodology: Potential pathogens of Enterobacteriaceae and Staphylococcus were screened in eight (8) species of processed fish. The investigation of the germs was carried out following the normative methods of microbiology. The identities of the strains were determined by API 20 E (BioMerieux S.A., France) and API STAPH (BioMerieux S.A., France) kits for Enterobacteriaceae and Staphylococcus species respectively. The uidA gene profile in Escherichia coli isolates was determined by simplex PCR. The identity of Staphylococcus aureus was confirmed by amplification of specific 23S rDNA regions and nuc gene profile with PCR. Results: A total of 235 fish samples were analyzed. A diversity of Enterobacteriaceae and Staphylococcus was detected. Twenty species of Enterobacteriaceae were identified among which, the most frequent were Escherichia coli, Salmonella sp, Raoultella ornithinolytica and Serratia odorifera, respectively in 22.6%, 4.3%, 28.9%, 17.4% of the samples analyzed. However, eleven species of Staphylococcus were identified among which, Staphylococcus xylosus, Staphylococcus aureus, Staphylococcus lugdunensis, and Staphylococcus sciuri were the most frequent with respective percentages of 47.7%, 23.4%, 12.8% and 10.6% of samples. For all the samples, the species frequently isolated were: Raoultella ornithinolytica, Escherichia coli, Serratia odorifera, Staphylococcus aureus, Staphylococcus xylosus, and Staphylococcus lugdunensis. The uidA gene specific to Escherichia coli was detected in 82.85% of strains (29/35). Amplification of the specific 23S rDNA region using staur primers was observed in 98% (49/50) of the isolated Staphylococcus aureus strains and the nuc gene was detected in 86% of Staphylococcus aureus strains. Conclusion: The isolated bacteria are potential pathogens involved in foodborne illnesses and intoxications. Effective sanitary safety systems must be implemented to guarantee the sanitary quality of fish supplied to consumers.